1. Technical Field
The present invention relates to a liquid jet head and liquid jet apparatus that are configured to jet droplets onto a recording medium to record information.
2. Related Art
In an ink-jet-method currently in use, a liquid jet head is configured to jet ink droplets, for example, onto recording paper to record a character or a figure, or to eject a liquid material to form a functional thin film on the surface of an element substrate. In the method, liquid such as ink or a liquid material is led to a channel from a liquid tank through a supply pipe, and a pressure is applied to the liquid filled in the channel such that the liquid is ejected as droplets from a nozzle communicating with the channel. When the droplets are ejected, the liquid jet head and the recording medium are moved to record a character or a figure or to form a functional thin film or three-dimensional structure having a predetermined shape.
The liquid jet head as described above is described in JP 2011-245833 A. FIG. 8 (FIG. 8 in JP 2011-245833 A) is a schematic top view of a liquid jet head 101 from which the cover plate is removed. An actuator substrate 102 includes ejection grooves C and non-ejection grooves D that are alternately arranged on the top surface, drive electrodes 109 that are installed on the side surfaces of the ejection grooves C and non-ejection grooves D, first terminal electrodes 110a that are electrically connected to the drive electrodes 109 of the ejection grooves C, and second terminal electrodes 110b that each are electrically connected to the drive electrode 109 installed on the side surface on the ejection groove C side of the two non-ejection grooves D holding an ejection groove C therebetween. Each of the ejection grooves C is formed from a front end FE to a position short of a rear end RE, and each of the non-ejection grooves D is formed from the front end FE to the rear end RE. A nozzle plate 105 is installed on the front end FE of the actuator substrate 102. A flexible substrate 103 is installed on a substrate surface 115 near the rear end RE of the actuator substrate 102.
A common wiring electrode 111a and a plurality of individual wiring electrodes 111b are formed on the surface on the actuator substrate 102 side of the flexible substrate 103. The common wiring electrode 111a is electrically connected to each of the first terminal electrodes 110a at each of the first connection points 116a. Each of the individual wiring electrodes 111b is electrically connected to each of the second terminal electrodes 110b at each of the second connection points 116b. Note that a cover plate (not illustrated in the drawing) is bonded to the substrate surface 115 of the actuator substrate 102. The cover plate covers a part of an upper opening in each of the ejection grooves C so as to form a channel that is to be filled with liquid. The cover plate includes a liquid chamber to be capable of supplying the liquid to each of the ejection grooves C. Nozzles 114 communicating with the ejection grooves C are formed on the nozzle plate 105. Note that an insulating layer 117 is installed between the common wiring electrode 111a and each of the non-ejection grooves D so as to prevent an electric short-circuit between the common wiring electrode 111a and each of the drive electrodes 109 installed on the side surfaces of the non-ejection grooves D.
The liquid jet head 101 is driven as described below. Liquid is filled in each of the ejection grooves C from the liquid chamber of the cover plate (not illustrated in the drawing). The common wiring electrode 111a is installed on a GND to supply a drive signal to the individual wiring electrodes 111b. This thickness-shear deforms a partition 107 among an ejection groove C and two non-ejection grooves D that hold the ejection groove C therebetween. This causes to eject the droplets from the nozzles 114 communicating with the ejection grooves C. Accordingly, supplying a drive signal to an arbitrary individual wiring electrodes 111b can simultaneously eject the droplets from the corresponding nozzles 114.
JP 2011-93105 A describes a liquid jet head on which a plurality of pressure chambers configured to eject droplets by applying a pressure to liquids, piezoelectric body layers bonded to the pressure chambers through vibrating plates, and a common wiring and individual wirings configured to apply a drive signal to the piezoelectric body layer are installed. The common wiring is commonly connected to the piezoelectric body layers whereas the individual wirings are individually connected to the piezoelectric body layers. Supplying a drive signal between the common wiring and the individual wiring deforms the piezoelectric body layer. The deformation momentarily changes the volume of the pressure chamber by deforming the vibrating plate. This causes to eject the droplets from the nozzle communicating with the pressure chamber.
JP 2011-93105 A describes that there is a problem in that heat is generated at the joint portion between the pad portion of the common wiring and the terminal portion of a film-shaped wiring board bonded to the pad portion because the increase in the number of the piezoelectric body layers driving the liquid jet head increases the current flowing through the common wiring.
The liquid jet head 101 in JP 2011-245833 A ejects the droplets simultaneously from the nozzles 114 communicating with the corresponding ejection grooves C by supplying the drive signal simultaneously to the individual wiring electrodes 111b. However, similarly to JP 2011-93105 A, the common wiring electrode 111a is electrically connected to all of the first terminal electrodes 110a. Thus, driving many ejection grooves C simultaneously causes overcurrent. This sometimes causes the common wiring electrode 111a to generate heat. When the common wiring electrode 111a is extended in width to avoid the overcurrent, the first terminal electrode 110a needs to be extended in the direction of the groove of the ejection groove C. This increases the size of the actuator substrate 102.